Diagnostic Aids

1997 Chevrolet Chevy Express G3500, Van Cargo, 6.5 FSECTION Diagnostic Aids
WARNING: This page is about a different variant/trim than selected.

When DTC P0125 is set, ECT sensor is skewed or engine thermostat does not operate properly. An intermittent may be caused by a poor connection, rubbed through wire insulation or a broken wire inside insulation. Inspect VCM harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If connections and harness are okay, observe scan tool connected between VCM connector terminals while wiggling related connectors and wiring harness. A change in display will indicate location of fault.

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.